Circuit-controlling system



Oct. 15, 1929. c. w. RICE CIRCUIT CONTROLLING SYSTEM Filed May 19. 1928 Inventor 2 Chester W. Rice alga His Attorney Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE CHESTER W. RICE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK CIRCUIT-CONTROLLING SYSTEM Application filed Kay 19,

My invention relates to the control of electric circuits particularly by means of vacuum switches having contacts operable into and out of circuit-closing engagement within a highly evacuated enclosing casing, and an important object of the invention is to protect against operation of the vacuum switch in the event that the vacuum of the switch should fail or become impaired.

For controlling high potential electric circuits such as used in the present day power transmission systemsa vacuum switch possesses certain inherent advantages over the various forms of oil switches ordinarily used in such service. In particular, the vacuum switch is both cheaper and simpler in construction, and furthermore, is capable of interrupting the circuit with practically no inductive disturbance, and with much less energy loss due to arcing than an oil switch of comparable capacity. However, the loss or impairment of the high degree of vacuum required for successful operation of the vacuum switch may render the latter quite useless as a circuit-interrupting device. Moreover, the loss of the vacuum is not perceptible as ordinarily would be the case with loss of oil in an oil switch.

Hence, the present invention. aims not onlyto provide a warning or alarm signal in case the vacuum of the switch should at any time become impaired, butalso automatically to make it impossible either to open or to close the. circuit through the switch having the im aired vacuum.

riefly, in accordance with the preferred form of the present invention, a plurality of vacuum switches are connected in series in the circuit so as jointly to interrupt the circuit when the switches are in normal operating condition. In addition, each of the vacuum switches is provided with a suitable vacuum gauge or device which operates responsively to the failure or impairment of the vacuum therein, and suitable disconnecting or short-circuiting switches are arranged to be automatically operated under the control of the vacuum responsive device so as 1928. Serial No. 279,154.

occurrence of failure or impairment of the vacuum therein or to short-circuit the vacuum switch in case the vacuum switch is closed when the vacuum becomes impaired. More over, an alarm or warning signal is arrange to be operated whenever the vacuum of he switch fails or becomes impaired. In this way the present invention eifectively prevents either the opening or closing of the circuit through the agency ofa vacuum switch having an impaired vacuum and at the same time provides a warning signal to indicate the unsafe conditionof the switch.

In the accompanying drawing the single figure illustrates diagrammatically a vacuum switch circuit controlling system embod ing the improvements of the present switch.

In the drawing the two vacuum-switches 10 and 11 are shown connected in series relation in the circuit I 1, L2. This circuit may be assumed to extend between a high volta e alternatin current source and a load circuit although t e present invention is not limited to. alternating current circuits.

Each of the vacuum switches 10 and 11 is shown as of the general type described in the copending applications of David C. Prince, No. 264,115 and No. 264,116, both filed March 23, 1928 and assigned to the assignee of my present invention. Briefly, this form of vacuum switch comprises 'a highly evacuated casing 127which encloses the relatively movable contacts 13, '14, of the switch. As brought out in the previously mentioned Prince applications, the casing 12 is exhausted 1 to an extremely low pressure, preferably of the order of 1/100 of a micron. In addition, the parts of the switch within the casing are specially treated to remove all residual and occluded. gases in order to prevent impairment of the vacuum during operation of the switch. This may be accomplished in any suitable way, examples of which are now known, as for example by heating the contacts and other parts to a high temperature during the exhaustion of the'casing 12 by high frequency induction action and also to disconnect the vacuum switch from the. by' electron bombardment, the walls of the circuit in case the switch is open upon the vessel being thoroughly deprived of occluded gas by baking in an oven for example during exhaustion.

In the preferred form of vacuum switch illustrated, each of the contacts 13 and 14 is mounted upon a corresponding supporting rod 15, 16, which extends through the opposite ends ofthe casing 12 and serves to carry the current to the respective contacts. The relative movement of the contacts within the casing is obtained by sealing the supporting rod 16 for the contact 14 to the casing by means of a yielding-'sylphon 17 which permits movement of the corresponding contact into and out of engagement with the other contact and at the same time provides an air-tight connection with the casing 12. If desired, the supporting rod 15 for the contact 13 also may be sealed to the casing 12 by means of the sylphon 18 in order to prevent transmission of shocks to the casing as described and claimed in the previously mentioned Prince application, Serial No. 264,115.

The movable contact 14 may be operated by any suitable means, although as shown in the drawing it is arranged to be operated by a high speed operating mechanism of the type described in the previously mentioned application. This mechanism comprises the spring 19 which strongly biases the contact 14 to the circuit opening position, together with the electromagnet 220, which serves to hold the contact 14 in the circuit closing position when it is operatedthereto by the electromagnetic closing mechanism 21. The holding electromagnet 20 cooperates with the armature 22 in holding the contact 14 closed and is provided with a releasing winding 23 which controls the holding effect of the electromagnet 20 to permit operation of the contact 14 to the circuit-opening position in accordance with its bias. This operating mechanism for the vacuum switch is more fully described andbroadly claimed in the Tritle Reissue Patent No.- 15,441, dated August 29, 1922, and provides for releasing the movable contact 14 with the utmost speed upon energization of the tripping winding 23. The particular form of lever mechanism associated with the armature 22 and the closing electromagnet 21 is constructed in accordance with the Tritle Patent No. 1,560,440, dated November 3, 1925, and permits free tripping of the vacuum switch in case the tripping winding 23 is operatively energized upon closure of the vacuum switch.

In accordance with the present invention the vacuum switch 10 is connected in the circuit L1, L2, through. the disconnecting switches 24 and 25 which are 'biased to the open position by the springs 26 and 27 re-' spectively. The disconnecting switch ,24 is maintained closed bythe electromagnetically actuated latch mechanism 28 and the corelec'tromagnetically actuated responding latch mechanism 29 serves to hold the switch 25 in the closed position. The disconnecting switches 24 and 25 are arranged to be operated under the control of the automatic vacuum-responsive apparatus 30 which is responsive to the condition of vacuum within the casing 12 so as to disconnect the switch 10 from the circuit in case the Vacuum of the switch fails when the switch is in the circuit-opening position, as will be described more fully hereinafter. Likewise, the switch 31 is connected to short-circuit the vacuum switch 10 under the control of the vacuumrcsponsive apparatus 30 in case the vacuum of the'switch fails when the switch is in the closed position. The switch 31 is biased to the short-circuiting position by the spring 32 and is held in the open position in which it is shown by the electromagnetically controlled latch mechanism 33.

The vacuum-responsive apparatus 30 as illustrated is of the thermocouple type and comprises a filament 40 which is heated from a suitable source, such for example as the battery B, and is enclosed within a chamber 41 in communication with the evacuated casing 12 so as to be subjected to the degree of vacuum obtained therein. The heat is dissipated from the filament 40 by radiationand by convectiondue t0 the gases withinthe evacuated casing. Thus, with a high degree of vacuum there will be very little gas present and the convection losses from the filament 40 will be practically negligible. However, if the vacuum fails or becomes impaired due to a leak in the casing or from any other cause, the convection current set' up in the gases within the casing quickly reduces the temperature of the filament 40.

In order to ascertain the temperature of the filament '40,.a thermocouple 42 is located in close proximity thereto and connected to operate the electro-responsive relay 43 in accordance with the current set up in the thermocouple 41 due to the temperature in the filament 40. Preferably a current-amplify ing device illustrated diagrammatically as 44 is providedfor amplifying the relatively small current supplied from the thermocouple 41 to the relay 43. The relay-43 preterably is of the type having a rotating coil 45 located between the magnetic poles indicated diagrammatically as N and S. A mirror 46 is carried by the rotating coil 45 so as to deflect light from the source L in ac-' cordance with the current su plied from'the thermocouple 42. The light beam controlled by the relay 43 isrendered effective to'operate the electroresponsive switch 47 through lay, such for example as the Wheatstone bridge arrangement 48, although a photoelectric cell or other form of light-responsive device may be employed if desired.

As shown the Wheatstone bridge lightresponsive means comprises the four resistors .the agency of [a suitable light-responsive re- R1, R2, R3, and R4, to which current is sup. plied from a suitable source such as the battery I32. At least one of the resistors, such as the resistor R1, is formed of a material which changes its resistance under the action of light, such for example as selenium. The \Vheatstone bridge arrangement may be enclosed within the suitable light-proof casing 49 having a window 50 arranged to receive light from the mirror 46 on the le-. lay 43.

Thus when the light from the source L is directed by the mirror 46 through the win dow 50 upon the resistance R1. the \Vheatstone bridge is unbalanced with the resulting flow of current through the operating winding of the switch 47. The whole arrangement of the vaciuim-responsive apparatus 30 is such that when the vacuum within the casing 12 is of the required high degree, the operating winding of the relay 43 assumes such a position that the mirror 46 directs the light from the source L away from the window 50 and projects light into the window 50 only when the vacuum of the switch 10 becomes impaired to such degree as to render the switch unlit for circuit-closing or circuit-opening service. A stop 56 is provided on the relay 43 to keep the light beam from going beyond the window 50 in case the vacuum becomes further impaired.

The vacuum-responsive apparatus just described not only provides an accurate and quick response to failure of the vacuum within the casing 12 of the vacuum switch, but also effectively serves to insulate the control apparatus from the vacuum switch where the latter is employed in extremely high voltage service. Thus the IVheatstone bridge resistance arrangement may be located remotely from and effectively insulated from the light-responsive relay 43.

In order to selectively control the disconnecting switches 24 and 25 and the short-circuiting switch 31, the vacuum switch 10 is provided with an auxiliary switch 51. This switch in conjunction with the electromagnetic switch 47 connects the battery B3 to energize the electromagnetically operated latches 2S and 29 to release the disconnecting switches 24 and 25 in case the switch 47 is operated due to failure of vacuum when the vacuum switch 10 is in the opening position as shown or to energize the electromagnet latch mechanism 33 of the short-circuiting switch 31 in case the vacuum fails when the switch 10 is in the circuit-closing position. In either case closure of the vacnum con trolled electroresponsive switch 47 completes the energizing circuit for the alarm signal 52 which may be either an electric lamp, semaphore, or other suitable alarm device.

It will be observed that the construction and arrangement of the vacuum switch 11 and the operating mechanism, disconnecting switches, short-circuit switch, and vacuum-responsive apparatus associated therewith is identical in all respects with that described in connection with the vacuum switch 10 and hence no additional description is deemed necessary.

The operation of the circuit-controlling system illustrated in the drawing is as follows: To close the circuit of the lines L1, L2, each of the vacuum switches 10, 11 is operated from the open position in which it is shown to the .closed position. This is accomplished by closing the push button switches 53 and 53 to energizefthe closing magnets 21 and 21 of the operating mechanism for the respective vacuum switches. This results in operating the armatures 22 and 22 into engagement with their respeta tive holding ma nets 20 and 20. \Vith the control switches at and 54 closed to energize the holding electromagnets 20 and 20 from a suitable direct current supply source indicated as and the armatures 22 and 22' are maintained in the attracted position and the movable contacts 14 and 14 of the vacuum switches are thereby held in engagement with the coo crating contacts 13 and 13.

In case o1 excessive current flow in the lines L1, L2, the overload relay 55 is opera tively energized from the current transformer T and closes its contacts to energize the tripping windings 23 and 23 of the vacuum switches 10 and 11 respectively from the supply cource indicated as and in the drawing. This results in the release of the armatures 22 and 22 and permits the biasing springs 19 and 19 to quickly operate the movable contacts 14 and 14 to the circuitopening position. WVith an alternating current circuit as illustrated and with the contacts 13 and 14 of suitable material, the current continues to flow between the contacts of the vacuum switches due to electron emission until he zero point of the wave is reached. Thereupon the circuit is interrupted with practically no inductive disturbance.

In case the vacuum of the switch 10 should fail or become impaired while the switch is in the open position in which it is shown in the drawing, the correspondng Vacuum-responsive apparatus 30 functions to direct the light from the source L upon the light-sensitive resistance R1 to unbalance the "Wheatstone bridge and thereby operatively energizing the corresponding protective relay 47. Closure of the contacts of the relay 47 with the vacuum switch 10 in the open position and the auxiliary control switch 51 inits corresponding lower position results in energizin the tripping electromagnets 28 and 29 o the disconnecting switches 26 and 27 respectively. This releases the disconnecting switches for operation to the circuitopening position in accordance with their bias thereby entirely disconnecting the switch 10 from the circuit L1, L2.

In a similar manner the vacuum-responsive device 30 and the corresponding control trol switch 51 in its upper position, operation.

of the vacuum-responsive device to close the protective relay 47 serves to energize the tripping magnet 33. This releases the short circuiting switch 31 which operates in accordance with its bias to short circuit the vacuum switch 10. In this way it is impossible to interrupt the circuit by means of switch 10 in case the vacuum thereof is defective. Likewise, it will be understood that with the switch 11 closed, the short-circuiting switch 31 is operated to the short-circuiting position in precisely the same way whenever the vacuum of switch 11 becomes impaired. It will be obvious that the signal light or other alarm device 52 or 52 willbe operated whenever the corresponding vacuum responsive device 30 and 30' functions to indicate a failure or impairment of the vacuum in vacuum switches 10 and 11 respectively.

While I have illustrated and described a preferred embodiment of the present invention, it will be understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

\Vhat I claim as new and desire to secur by Letters Patent of the United States, is,--

1. The combinationof a vacuum switch having relatively movable contacts within an evacuated casing, a switch for short-circuiting said contacts and means responsive to the condition of vacuum within said casing for controlling the operation of the short-circuit ing switch. V

2. In a circuit controlling device, the combination of a vacuum switch having relatively movable contacts within an evacuated casing, means responsive to an electrical condition of the circuit for automatically operating the contacts, a switch for short-circuiting said contacts, and means res onsive to impairment of the vacuum wit iin said casing for operating said short-circuiting switch to render operation of the contacts ineffective to control the circuit.

3. In a circuit controlling device, the combination of a vacuum switch having relatively movable contacts within an evacuated cas ing for closing and opening the circuit, means responsive to the condition of vacuum within said casing, and switch mechanism controlled by said means for rendering the vacuum switch inefiective to open and close vacuum switch ling the operation of the switch to open and close the circuit.

5. In a circuit controlling device, the com bination of a vacuum switch having relatively movable contacts within an evacuated casing, switch mechanism for disconnecting the vacuum switch from the circuit, independently operable switch mechanism for short circuiting the vacuum switch, means responsive to the condition of vacuum within said casing for operating said disconnecting switch mechanism upon impairment of the vacuum within said casing when the vacuum switch is open and for operating said short circuiting switch mechanism upon impairment of the vacuum within said casing when the vacuum switch is closed. 7

' 6. In a circuit controlling device, the com bination of a vacuum switch having relatively movable contactswithin an evacuated casing, electroresponsive switch mechanism for disconnecting the said contacts from the circuit controlled by the vacuum switch, electro responsive switch mechanism for short circuiting the relatively movable contacts of the vacuum switch, auxiliary control switch mechanism operable to one position when the vacuum switch is closed and to another position when the vacuum switch is open, circuit controlling means responsive to the condition ofyacuum within said casing, and connections jomtly controlled by said auxiliary switch mechanism and said vacuum responsive means for effecting operation of said electroresponsive disconnecting switch mechanism upon impairment of the vacuum within said casing when the vacuum switch is open and for effectmg operation of said electroresponsive short circuiting switch mechanism upon impairment of the vacuum within said casing when the vacuum switch is closed.

7. In a circuit controlling device, the combination of avacuum switch having relatively movable contacts within an evacuated casing, electroresponsive means for separating said relatively movable contacts in response to predetermined electrical conditions in the circuit controlled by the vacuum switch, electro responsive switch mechanism for disconnecting the relatively movable contacts of the rom the circuit controlled thereby, electroresponsive switch mechanism for short circuiting the relatively movable contacts of the vacuum switch, means responsive to the condition of vacuum within the evacuated casing of the vacuum switch ineluding a light sensitive circuit controlling element, electroresponsive switch mechanism controlled by said element, auxiliary switch mechanism associated with the vacuum switch to be operated to one circuit controlling po-. sition when the vacuum switch is open and to another circuit controllin position when the vacuum switch is close and connections jointly controlled b said auxiliary switch mechanism and said ight sensitive controlled switch mechanism 'for efiecting operation of said disconecting switch mechanism upon impairment of the vacuum within said evacuated casing when the vacuum switch is in the open positionand for efiecting operation oi said short circuiting switch mechanism upon 1mpairment of the vacuum within said casing when the vacuum switch is in the circuit closing position.

8. A circuit controlling system comprising a pair of vacuum switches connected in series relation to jointly control the opening and closing of the circuit when the vacuum conditions of the switches are normal, auxiliary switch mechanism associated with each vacuum switch for rendering the switch ineffective to control the circuit and thereby place the circuit exclusively under the control of the other switch, and means responsive to the condition of vacuum in each switch for controlling the corresponding auxiliary switch mechanism associatedtherewith.

9. The combination of a vacuum switch having relatively movable contacts withinan evacuated casing for controlling a circuit an alarm mechanism automatically operable ,in response to. a predetermined impairment of the vacuum in said casing, and means associated with said alarm mechanism for rendering the vacuum switch ineffective to control the circuit. a

10. The combination of a vacuum switch having relative movable contacts Within an evacuated casing for controlling a circuit an alarm mechanism including a light sensitive element automatically operable in response to a predetermined impairment of the vacuum in said casing, and means associated with said alarm mechanism for rendering the vacuum switch ineffective to control the circuit.

In witness whereofl I have hereunto set my hand this 18th day of May, 1928. CHESTER W. RICE. 

